Fail to install npm package "npm ERR! errno -4048"

Kill whatever process is locking your files

It seems like this kind of error can be caused by a file permissions lock - I experienced something very similar (the same ERRNO: -4048) when installing whatwg-fetch.

I found that a Visual Studio instance I had open at the same time was acquiring all kinds of files which it didn't need. Once I closed that down, the install worked perfectly.

This may be a quickly-checked possible cause to eliminate before moving on to more drastic measures...

if you still have troubles with this error and maybe you upgrade the node version to 5.4 > ... that version presents an error. here the solution that basically consist in downgrade node version

In Windows will be:

npm install -g [email protected]

That's works for me.